SGS OR GSGSG PATTERN FOR SIGNAL TRANSMITTING CHANNEL, AND PCB ASSEMBLY, CHIP PACKAGE USING SUCH SGS OR GSGSG PATTERN
A substrate having multiple metal layers is disclosed. The substrate includes a plurality of metal layers disposed in different levels. The plurality of metal layers includes a lower metal layer, a middle metal layer situated overlying the lower layer, and an upper metal layer situated overlying the middle metal layer. A solder mask covers the upper metal layer. A reference plane is arranged in the lower metal layer. A trio of signal traces is arranged in the middle metal layer. The trio of signal traces comprises at least a pair of differential signal traces. A plurality of reference nets is arranged in the middle metal layer.
This application is a continuation-in-part of U.S. application Ser. No. 14/992,011 filed Jan. 10, 2016. U.S. application Ser. No. 14/992,011 is a division of U.S. application Ser. No. 13/892,323 filed May 13, 2013, which itself claims the benefits from U.S. provisional application No. 61/665,267 filed 2012 Jun. 27, U.S. provisional application No. 61/669,898 filed 2012 Jul. 10, and U.S. provisional application No. 61/675,605 filed 2012 Jul. 25.
BACKGROUNDThe present invention relates to improved signal transmitting channel with SGS or GSGSG pattern for high-speed signaling applications. This channel design can be implemented in, for example, printed circuit boards (PCBs), PCB assembly (PCBA), chip packages such as leadframe packages or the like, for both differential-mode impedance (Zdiff) and common-mode impedance (Zcom) matching.
As known in the art, semiconductor integrated circuit (IC) chips have input/output (I/O) pads that are connected to external circuitry in order to function as part of an electronic system. The connection media may be an array of metallic leads such as a leadframe or a support circuit such as a ball grid array (BGA) substrate. Wire bonding and flip-chip bonding are two widely used connection techniques. In wire bonding approach, wires are bonded, one at a time, from the chip to external circuitry by ultrasonic or thermocompression processes. During wire bonding, mechanical force such as pressure or a burst of ultrasonic vibration and elevated temperature are typically required to accomplish metallurgical welding between the wires or bumps and the designated surface.
Flip-chip bonding involves providing pre-formed solder bumps on the pads, flipping the chip so that the pads face down and are aligned with and contact matching bond sites, and melting the solder bumps to wet the pads and the bond sites. After the solder reflows, it is cooled down and solidified to form solder joints between the pads and the bond sites. A major advantage of flip-chip bonding over wiring bonding is that it provides shorter connection paths between the chip and the external circuitry, and therefore has better electrical characteristics such as less inductive noise, cross-talk, propagation delay and waveform distortion.
A leadframe typically includes a plurality of metal leads temporarily held together in a planar arrangement about a central region during package manufacture by a rectangular frame. A die pad is supported in the central region by a plurality of tie bars that attach to the frame. The leads extend from a first end integral with the frame to an opposite second end adjacent to, but spaced apart from, the die pad. During package manufacture, a semiconductor die is attached to the die pad. Wire-bonding pads on the die are then connected to selected ones of the inner leads by fine, conductive bonding wires to convey power, ground or signals between the die and the leads. A protective body of an epoxy resin is molded over the assembly to enclose and seal the die, the inner leads, and the wire bonds against harmful environmental elements. The rectangular frame and the outer ends of the leads are left exposed outside of the body, and after molding, the frame is cut away from the leads and discarded, and the outer ends of the leads are appropriately formed for interconnection of the package with an external printed circuit board.
A semiconductor chip can generate or receive a high-speed I/O signal at an I/O cell and may conduct the signal to or from a package terminal. The high-speed I/O signals may travel on transmission lines that are intended to maintain signal fidelity over a distance. Signal integrity is a set of measures of the quality of an electrical signal. Signal integrity engineering is an important activity at all levels of electronics packaging and assembly, from internal connections of an IC, through the package, the printed circuit board (PCB), the backplane, and inter-system connections. In nanometer technologies at 0.13 μm and below, unintended interactions between signals (e.g. crosstalk) became an important consideration for digital design. At these technology nodes, the performance and correctness of a design cannot be assured without considering noise effects.
The main cause of signal integrity problems is crosstalk. This is primarily due to coupling capacitance, but in general it may be caused by mutual inductance, substrate coupling, non-ideal gate operation, and other sources. The fixes normally involve changing the sizes of drivers and/or spacing of wires. In digital ICs, noise in a signal of interest arises primarily from coupling effects from switching of other signals. Increasing interconnect density has led to each wire having neighbors that are physically closer together, leading to increased coupling capacitance between neighboring nets. Larger mutual capacitance and mutual inductance also induce larger common-mode impedance and smaller differential impedance. The signal reflection also causes poor signal integrity due to impedance mismatch.
As circuits have continued to shrink in accordance with Moore's law, some effects have conspired to make noise problems worse. For example, to keep resistance tolerable despite decreased width, modern wire geometries are thicker in proportion to their spacing. This increases the sidewall capacitance at the expense of capacitance to ground, hence increasing the induced noise voltage. These effects have increased the interactions between signals and decreased the noise immunity of digital circuits. This has led to noise being a significant problem for digital ICs and high-speed signaling applications.
As a consequence of the low impedance required by matching, PCB signal traces carry much more current than their on-chip counterparts. This larger current induces crosstalk primarily in a magnetic, or inductive, mode, as opposed to a capacitive mode. The signal itself and its returning signal current path are equally capable of generating inductive crosstalk. Although differential trace pairs may help to reduce these effects, however, in some cases, there are still drawbacks to be overcome. For example, in leadframe packages or circuit boards such as 2-layer PCBs, the lack of a near reference plane (e.g. power plane or ground plane) leads to larger mutual inductance and capacitance, this in turns, causes smaller differential-mode impedance (Zdiff) and larger common-mode impedance (Zcom), which are undesirable in high-speed signal transmission applications such as data transmission through interfaces that are compatible with Mobile High-Definition Link (MHL) specification.
SUMMARYIt is one objective of this invention to provide an improved semiconductor circuit structure with improved performance, better signal integrity and fidelity.
To these ends, according to one aspect of the present invention, there is provided printed circuit board (PCB) assembly including a PCB comprising a core substrate, a plurality of conductive traces on a first surface of the PCB, and a ground layer on the second surface of the PCB, wherein the conductive traces comprise a pair of differential signal traces; an intervening reference trace disposed between the differential signal traces; a connector at one end of the plurality of conductive traces; and a semiconductor package mounted on the first surface at the other end of the plurality of conductive traces.
From another aspect of this invention, a leadframe package is provided. The leadframe package includes a die pad; a semiconductor die mounted on the die pad; a plurality of leads disposed in a first horizontal plane along peripheral edges of the die pad; a reference inner lead intervening between two adjacent, successive high-speed signal leads of the leads; a ground bar downset from the first horizontal plane to a second horizontal plane; a plurality of tie bars extending outward from the four corners of the die pad; a plurality of first bonding wires for electrically connecting the semiconductor die to the leads respectively; and a molding compound encapsulating the semiconductor die, the first bonding wires, the leads, the ground bar, the tie bars, and the die pad, wherein the die pad is exposed within a bottom surface of the molding compound.
From still another aspect of this invention, a quad-flat non-leaded (QFN) package includes a die pad; a semiconductor die mounted on the die pad; a plurality of leads disposed in a horizontal plane along peripheral edges of the die pad, wherein each lead comprises an exposed lead and an embedded, half-etched inner lead adjoined to the exposed lead; an intervening reference lead between two adjacent, successive high-speed leads of the plurality of leads; a plurality of tie bars extending outward from the die pad; a plurality of first bonding wires for electrically connecting the semiconductor die to the leads respectively; and a molding compound at least encapsulating the semiconductor die, the first bonding wires, the leads, the tie bars, and the die pad, wherein the die pad is exposed within a bottom surface of the molding compound.
From yet another aspect of this invention, a leadframe package includes a die pad; a semiconductor die mounted on the die pad; a plurality of leads disposed in a horizontal plane along peripheral edges of the die pad; a plurality of tie bars extending outward from the die pad; a plurality of bonding wires for electrically connecting the semiconductor die to the leads respectively; a molding compound encapsulating the semiconductor die, the bonding wires, the leads, the tie bars, and the die pad, wherein the die pad is exposed within a bottom surface of the molding compound; and an extended metal layer on a bottom surface of the leadframe package.
From yet another aspect of this invention, a leadframe package includes a die pad; a semiconductor die mounted on the die pad; a plurality of leads disposed in a first horizontal plane along peripheral edges of the die pad; a lead-lock tape transversely attached across the plurality of leads around the die pad; a metal layer disposed on the lead-lock tape; a ground bar downset from the first horizontal plane to a second horizontal plane; a plurality of tie bars extending outward from the die pad; a plurality of first bonding wires for electrically connecting the semiconductor die to the leads respectively; and a molding compound at least encapsulating the semiconductor die, the first bonding wires, the leads, the lead-lock tape, the metal layer, the ground bar, the tie bars, and the die pad, wherein the die pad is exposed within a bottom surface of the molding compound.
According to another aspect of the invention, a substrate having multiple metal layers is disclosed. The substrate includes a plurality of metal layers disposed in different levels. The plurality of metal layers comprises a lower metal layer, a middle metal layer situated overlying the lower layer, and an upper metal layer situated overlying the middle metal layer. A solder mask covers the upper metal layer. A reference plane is arranged in the lower metal layer. A trio of signal traces is arranged in the middle metal layer. The trio of signal traces comprises at least a pair of differential signal traces. A plurality of reference nets is arranged in the middle metal layer.
According to one embodiment, the substrate includes a plurality of metal layers disposed in different levels. The plurality of metal layers comprises a lower metal layer, a middle metal layer situated overlying the lower layer, and an upper metal layer situated overlying the middle metal layer. A solder mask covers the upper metal layer. A reference plane is arranged in the lower metal layer. A trio of signal traces comprising a first signal trace arranged in the upper metal layer and a second signal trace and a third signal trace arranged in the middle metal layer is provided. The trio of signal traces comprises at least a pair of differential signal traces. A first reference net is arranged in the middle metal layer between the second signal trace and the third signal trace and directly under the first signal trace.
According to one embodiment, the substrate includes a plurality of metal layers disposed in different levels. The plurality of metal layers comprises a lower metal layer, a first middle metal layer situated overlying the lower layer, a second middle metal layer situated overlying the first middle metal layer, and an upper metal layer situated overlying the second middle metal layer. A first reference plane is arranged in the lower metal layer. A second reference plane is arranged in the upper metal layer. A trio of signal traces comprising a first signal trace arranged in the second middle metal layer, and a second signal trace and a third signal trace arranged in the first middle metal layer is provided. The trio of signal traces comprises at least a pair of differential signal traces. A pair of reference nets is arranged in the second middle metal layer. The pair of reference nets sandwich about the first signal trace.
According to one embodiment, the substrate includes a plurality of metal layers disposed in different levels. The plurality of metal layers comprises a lower metal layer, a middle metal layer situated overlying the lower layer, and an upper metal layer situated overlying the middle metal layer. A solder mask covers the upper metal layer. A reference plane is arranged in the lower metal layer. A trio of signal traces comprising a first signal trace arranged in the middle metal layer, and a second signal trace and a third signal trace arranged in the upper metal layer is provided. The trio of signal traces comprises at least a pair of differential signal traces. A first pair of reference nets is arranged in the middle metal layer. The first pair of reference nets sandwich about the first signal trace.
According to one embodiment, the substrate includes a plurality of metal layers disposed in different levels. The plurality of metal layers comprises a lower metal layer, a first middle metal layer situated overlying the lower layer, a second middle metal layer situated overlying the first middle metal layer, a third middle metal layer situated overlying the second middle metal layer, and an upper metal layer situated overlying the third middle metal layer. A first reference plane is arranged in the lower metal layer. A second reference plane is arranged in the first middle metal layer. A trio of signal traces comprising a first signal trace arranged in the second middle metal layer, a second signal trace arranged in the third middle metal layer, and a third signal trace arranged in the upper metal layer, is provided. The trio of signal traces comprises at least a pair of differential signal traces.
These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.
The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. In the drawings:
One or more implementations of the present invention will now be described with reference to the attached drawings, wherein like reference numerals are used to refer to like elements throughout, and wherein the illustrated structures are not necessarily drawn to scale.
The present invention pertains to an improved channel for transmitting, for example, differential mode and common mode signals simultaneously, which is suited for high-speed signal transmission applications such as data transmission interfaces that are compatible with Mobile High-Definition Link (MHL) specification. The invention may be embodied in various forms, for example, in printed circuit boards (PCBs), PCB assembly (PCBA), chip packages such as leadframe packages, or any place in the signal transmission channel or connector device that involves crowded or paired high-speed or high frequency traces (in PCBs) or leads (in packages), for example, paired MHL+ and MHL− differential signal traces in PCBs.
The MHL specification is a high-definition (HD) video and digital audio interface for connecting mobile phones and portable devices to HDTVs and other home entertainment products. It utilizes established connectors and features a single cable with a 5-pin interface, supports 1080p HD video and digital audio and simultaneously provides power to the mobile device. It also enables the TV remote to control the mobile phone and access its contents.
In order to conform to the MHL specification in the high-speed signal transmission applications, a costly 4-layer PCBs and/or BGA package substrates are typically employed in the MHL enable interface devices. By utilizing the inventive SGS or GSGSG channel circuit design, both the differential-mode impedance (Zdiff) and common-mode impedance (Zcom) can conform to the MHL specification, which Zdiff is close to 100Ω (±15Ω) and Zcom is close to 30Ω (±6Ω), which can be realized by using a cost-effective 2-layer PCB, while the routing space on the 2-layer PCB is not sacrificed. However, it is understood that the present invention may be applicable to multi-layer PCBs.
Hereinafter, the term “2-layer PCB” refers to a PCB having only one layer of conductive traces on each side of the core substrate of the PCB, and the term “PCBA” refers to a PCB assembly including at least one electronic component such as a chip or package mounted on a component side of the PCB. The term “SGS” refers to a circuit layout structure comprising an intervening reference trace or lead sandwiched by a pair of high-speed/high-frequency signal traces or leads, which operates greater than 1 Gb/s. The term “GSGSG” refers to a circuit layout structure comprising the aforesaid SGS pattern and a pair of ground guard lines sandwiching about the SGS pattern.
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According to the embodiment, the ground guard lines 112a and 112b both have a line width GW1 of about 20 mils, the differential signal traces 110a and 110b both have a line width W of about 20 mils, and the intervening reference trace 114 may have a line width GW2 of greater than or equal to 3 mils, for example, about 5 mils. According to the embodiment, the spacing GS1 may be about 6 mils, for example. According to the embodiment, the spacing GS2 may be about 4 mils, for example. A channel span D is defined as the combination of the line widths W of the differential signal traces 110a and 110b, the line width GW2 of the intervening reference trace 114, and the spacing GS2 between the intervening reference trace 114 and the differential signal trace 110a and between the intervening reference trace 114 and the differential signal trace 110b. According to the embodiment, for example, the channel span D may be about 53 mils (D=2×W+GW2+2×GS2). With such unique SGS (or GSGSG) configuration, a simulated Zdiff/Zcom of about 89/27Ω can be achieved (impedance simulation in 2-layer PCB using ANSYS Q2D).
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The above-discussed SGS or GSGSG configuration may be applicable to BGA or 2-layer TFBGA (thin fine-pitch BGA) package substrates. As shown in
The above-discussed SGS configuration may be applicable to leadframe packages such as an exposed die pad (E-pad) leadframe package. The E-pad leadframe package exposes the bottom surface of the die pad to the outside of the encapsulation body. The exposed die pad may act as a heat sink and can improve the heat-dissipation efficiency. Typically, the exposed die pad is electrically connected to a ground plane of the external PCB or mother board. Among others, an E-pad low-profile quad flat package (LQFP) is known as a low-cost solution for multimedia chips.
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The E-pad leadframe package 300 further comprises a plurality of bonding wires 330 for electrically connecting the semiconductor die 320 to the leads 310 and a plurality of bonding wires 340 for electrically connecting the ground bar 303 to the respective ground pads (not explicitly shown) of the semiconductor die 320. A molding compound or mold body 350 at least encapsulates the semiconductor die 320, the bonding wires 330 and 340, the inner leads 310′ of the leads 310, the ground bar 303, the tie bars 304, and partially the die pad 302 such that the bottom surface of the die pad 302 is exposed within the bottom surface of the molding compound 350. The inner lead 310′ is the portion of each of the leads 310 that is embedded within the molding compound 350. The inner lead 310′ has a length L. The outer lead 310″ is the portion of each of the leads 310 that protrudes from the edges of the molding compound 350.
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Although an E-pad leadframe package is demonstrated, it is to be understood that the present invention should not be limited to such applications. For example, the present invention may be applicable to a non-exposed pad leadframe package.
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To further reduce the lead common-mode impedance, an additional ground layer may be incorporated with the exposed die pad of the leadframe package. As shown in
The additional ground plane may be incorporated within the leadframe package and may be embedded within the molding compound. As shown in
For example, the substrate 5 may comprise a core substrate 10. At least three metal layers M1˜M3 in different levels are disposed on one side of the core substrate 10. For the sake of simplicity, the metal traces embedded in the core substrate 10 are not explicitly shown in
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According to the embodiment of the invention, a trio of signal traces that is composed of a first signal trace S1, a second signal trace S2, and a third signal trace S3 is arranged in the middle metal layer M2 and on the insulating build-up layer 210. According to the embodiment of the invention, the trio of signal traces comprises at least a pair of differential signal traces. According to the embodiment of the invention, the trio of signal traces may be operated greater than 1 Gb/s. According to the embodiment of the invention, the first signal trace S1, the second signal trace S2, and the third signal trace S3 are coplanar and are arranged with a pitch of 400 micrometers.
According to the embodiment of the invention, a plurality of reference nets RN1˜RN4 is arranged in the middle metal layer M2. The plurality of reference nets RN1˜RN4 may be electrically connected to ground or power. According to the embodiment of the invention, the trio of signal traces S1˜S3 and the plurality of reference nets RN1˜RN4 are coplanar. The first signal trace S1, the second signal trace S2, and the third signal trace S3 are separated by the plurality of reference nets RN1˜RN4. The first signal trace S1 is interposed between the reference net RN1 and the reference net RN2, the second signal trace S2 is interposed between the reference net RN2 and the reference net RN3, and the third signal trace S3 is interposed between the reference net RN3 and the reference net RN4.
An insulating build-up layer 220 is laminated on the middle metal layer M2. For example, the insulating build-up layer 220 may comprise prepreg material such as 2113 prepreg, but is not limited thereto. The upper metal layer M1 is disposed on the insulating build-up layer 220. A solder mask 130 covers the upper metal layer M1 and the exposed upper surface of the insulating build-up layer 220.
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According to the embodiment, for example, the line widths W1, W2, and W3 of the signal traces S1˜S3 may be 100 micrometers. According to the embodiment, for example, the line widths GW1, GW2, GW3, and GW4 of the reference nets RN1˜RN4 may be 100 micrometers. According to the embodiment, for example, the spacing GS1, GS2, GS3, GS4, GS5, GS6 between the reference nets RN1˜RN4 and the signal traces S1˜S3 may be 100 micrometers. According to the embodiment, for example, the horizontal span D″ may be about 1200 micrometers. According to the embodiment, the horizontal span D″ is preferably smaller than or equal to 3000 micrometers, which is smaller than that of signal traces S1˜S3 arranged in the upper metal layer M1. Thus the routing density of signal traces can be increased.
According to the applications with better signal quality, the differential-mode impedances Zdiff (S1, S2), Zdiff (S3, S1), and Zdiff (S2, S3) of the trio of signal traces should range between 85Ω and 115Ω (85Ω<Zdiff (S1, S2), Zdiff (S3, S1), and Zdiff (S2, S3)≤115Ω). The target differential-mode impedance (Zdiff) is 100Ω. The common-mode impedances Zcom (S1, S2), Zcom (S3, S1), and Zcom (S2, S3) of the trio of signal traces should range between 20Ω and 30Ω (20Ω≤Zcom (S1, S2), Zcom (S3, S1), and Zcom (S2, S3)≤30Ω). The target common-mode impedance (Zcom) is 25Ω. The target single-ended impedance (z0) is 50Ω.
According to the simulation results of the embodiment for dual coupled impedance (impedance simulation using ANSYS Q2D), a single-ended impedance Z0 of about 49.1Ω can be achieved. A simulated Zdiff (S1, S2) of about 96.4Ω, a simulated Zdiff (S3, S1) of about 97.8Ω, and a simulated Zdiff (S2, S3) of about 96.4Ω can be achieved. A simulated Zcom (S1, S2) of about 25.0Ω, a simulated Zcom (S3, S1) of about 24.6Ω, and a simulated Zcom (S2, S3) of about 25.0Ω can be achieved.
According to the embodiment of the invention, in the region directly above the horizontal span D″ between the first signal trace S1 and the third signal trace S3, no metal trace or plane is disposed in the upper metal layer M1. In addition, the reference nets RN1˜RN4 may be electrically connected to the reference plane RP through the conductive vias V1˜V4, respectively. According to the embodiment of the invention, the conductive vias V1˜V4 are formed in the insulating build-up layer 210.
The trio signal trace layout as depicted in
Likewise, the substrate 6a may comprise a core substrate 10. At least three metal layers M1˜M3 in different levels are disposed on one side of the core substrate 10. For the sake of simplicity, the metal traces embedded in the core substrate 10 are not explicitly shown in
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According to the embodiment of the invention, a trio of signal traces that is composed of a first signal trace S1, a second signal trace S2, and a third signal trace S3 is arranged in the upper metal layer M1 and the middle metal layer M2. According to the embodiment of the invention, the trio of signal traces comprises at least a pair of differential signal traces. According to the embodiment of the invention, the trio of signal traces may be operated greater than 1 Gb/s. According to the embodiment of the invention, the second signal trace S2 and the third signal trace S3 are coplanar.
According to the embodiment of the invention, a reference net RN1 is arranged in the middle metal layer M2. The reference net RN1 may be electrically connected to ground or power. According to the embodiment of the invention, the second signal trace S2, the third signal trace S3 and the reference net RN1 are coplanar. The second signal trace S2, and the third signal trace S3 are separated by the reference net RN1. The reference net RN1 is interposed between the second signal trace S2 and the third signal trace S3.
An insulating build-up layer 220 is laminated on the middle metal layer M2. For example, the insulating build-up layer 220 may comprise prepreg material such as 2113 prepreg, but is not limited thereto. The insulating build-up layer 220 covers the second signal trace S2, the third signal trace S3 and the reference net RN1. The upper metal layer M1 is disposed on the insulating build-up layer 220. A solder mask 130 covers the upper metal layer M1 and the exposed upper surface of the insulating build-up layer 220.
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According to the embodiment, for example, the line width W1 of the first signal trace S1 may be 100 micrometers and the line widths W2 and W3 of the signal trace S2˜S3 may be 114 micrometers. According to the embodiment, the line width W1 of the first signal trace S1 is smaller than or equal to that of the reference net RN1. For example, the line width GW1 of the reference net RN1 may be 400 micrometers. According to the embodiment, for example, the spacing GS1, GS2 between the reference net RN1 and the signal traces S2˜S3 may be 100 micrometers. According to the embodiment, for example, the horizontal span D″ may be about 828 micrometers. According to the embodiment, the horizontal span D″ is smaller than or equal to 3000 micrometers, and the routing density of signal traces can be increased.
According to the simulation results of the embodiment for dual coupled impedance (impedance simulation using ANSYS Q2D), a single-ended impedance Z0 of about 49.8Ω˜50.1Ω can be achieved. A simulated Zdiff (S1, S2) of about 95.2Ω, a simulated Zdiff (S3, S1) of about 96.2Ω, and a simulated Zdiff (S2, S3) of about 99.5Ω can be achieved. A simulated Zcom (S1, S2) of about 26.0Ω, a simulated Zcom (S3, S1) of about 26.1Ω, and a simulated Zcom (S2, S3) of about 25.2Ω can be achieved.
According to the embodiment, the reference net RN1 may be electrically connected to the reference plane RP through the conductive vias V1˜V2. According to the embodiment of the invention, the conductive vias V1˜V2 are formed in the insulating build-up layer 210.
Likewise, the substrate 6b may comprise a core substrate 10. At least three metal layers M1˜M3 in different levels are disposed on one side of the core substrate 10. For the sake of simplicity, the metal traces embedded in the core substrate 10 are not explicitly shown in
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According to the embodiment of the invention, a trio of signal traces that is composed of a first signal trace S1, a second signal trace S2, and a third signal trace S3 is arranged in the upper metal layer M1 and the middle metal layer M2. According to the embodiment of the invention, the trio of signal traces comprises at least a pair of differential signal traces. According to the embodiment of the invention, the trio of signal traces may be operated greater than 1 Gb/s. According to the embodiment of the invention, the second signal trace S2 and the third signal trace S3 are coplanar.
According to the embodiment of the invention, a reference net RN1, a reference net RN2 and a reference net RN3 are arranged in the middle metal layer M2. The reference nets RN1˜RN3 may be electrically connected to ground or power. According to the embodiment of the invention, the second signal trace S2, the third signal trace S3 and the reference nets RN1˜RN3 are coplanar. The second signal trace S2, and the third signal trace S3 are separated by the reference net RN1. The reference net RN1 is interposed between the second signal trace S2 and the third signal trace S3.
Likewise, an insulating build-up layer 220 is laminated on the middle metal layer M2. For example, the insulating build-up layer 220 may comprise prepreg material such as 2113 prepreg, but is not limited thereto. The insulating build-up layer 220 covers the second signal trace S2, the third signal trace S3 and the reference nets RN1˜RN3. The upper metal layer M1 is disposed on the insulating build-up layer 220. A solder mask 130 covers the upper metal layer M1 and the exposed upper surface of the insulating build-up layer 220.
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According to the embodiment, for example, the line widths W1˜W3 of the signal traces S1˜S3 may be 100 micrometers. According to the embodiment, the line width W1 of the first signal trace S1 is smaller than or equal to that of the reference net RN1. For example, the line width GW1 of the reference net RN1 may be 400 micrometers. The line widths GW2˜GW3 of the reference nets RN2˜RN3 may be 100 micrometers. According to the embodiment, for example, the spacings GS1˜GS4 may be 100 micrometers. According to the embodiment, for example, the horizontal span D″ may be about 1200 micrometers. According to the embodiment, the horizontal span D″ is smaller than or equal to 3000 micrometers, and the routing density of signal traces can be increased.
According to the simulation results of the embodiment for dual coupled impedance (impedance simulation using ANSYS Q2D), a single-ended impedance Z0 of about 49.1Ω-49.9Ω can be achieved. A simulated Zdiff (S1, S2) of about 96.2Ω, a simulated Zdiff (S3, S1) of about 95.0Ω, and a simulated Zdiff (S2, S3) of about 97.8Ω can be achieved. A simulated Zcom (S1, S2) of about 25.8Ω, a simulated Zcom (S3, S1) of about 25.4Ω, and a simulated Zcom (S2, S3) of about 24.7Ω can be achieved.
According to the embodiment, the reference net RN1, the reference net RN2 and the reference net RN3 may be electrically connected to the reference plane RP through the conductive vias V1˜V3, respectively. According to the embodiment of the invention, the conductive vias V1˜V3 are formed in the insulating build-up layer 210.
Likewise, the substrate 6c may comprise a core substrate 10. At least three metal layers M1˜M3 in different levels are disposed on one side of the core substrate 10. For the sake of simplicity, the metal traces embedded in the core substrate 10 are not explicitly shown in
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According to the embodiment of the invention, a trio of signal traces that is composed of a first signal trace S1, a second signal trace S2, and a third signal trace S3 is arranged in the upper metal layer M1 and the middle metal layer M2. According to the embodiment of the invention, the trio of signal traces comprises at least a pair of differential signal traces. According to the embodiment of the invention, the trio of signal traces may be operated greater than 1 Gb/s. According to the embodiment of the invention, the second signal trace S2 and the third signal trace S3 are coplanar.
According to the embodiment of the invention, a reference net RN1 is arranged in the middle metal layer M2. A reference net RN2 and a reference net RN3 are arranged in the upper metal layer M1. The reference nets RN1˜RN3 may be electrically connected to ground or power. According to the embodiment of the invention, the second signal trace S2, the third signal trace S3 and the reference net RN1 are coplanar. The second signal trace S2 and the third signal trace S3 are separated by the reference net RN1. The reference net RN1 is interposed between the second signal trace S2 and the third signal trace S3. The first signal trace S1, the reference net RN2 and the reference net RN3 are coplanar.
Likewise, an insulating build-up layer 220 is laminated on the middle metal layer M2. For example, the insulating build-up layer 220 may comprise prepreg material such as 2113 prepreg, but is not limited thereto. The insulating build-up layer 220 covers the second signal trace S2, the third signal trace S3 and the reference net RN1. The upper metal layer M1 is disposed on the insulating build-up layer 220. A solder mask 130 covers the upper metal layer M1 and the exposed upper surface of the insulating build-up layer 220.
In
According to the embodiment, for example, the line width W1 of the first signal trace S1 may be 88 micrometers. The line widths W2˜W3 of the signal traces S2˜S3 may be 76 micrometers. According to the embodiment, the line width W1 of the first signal trace S1 is smaller than or equal to that of the reference net RN1. For example, the line width GW1 of the reference net RN1 may be 200 micrometers. The line widths GW2˜GW3 of the reference net RN2˜RN3 may be 100 micrometers. According to the embodiment, for example, the spacing GS1˜GS2 may be 150 micrometers. According to the embodiment, for example, the horizontal span D″ may be about 652 micrometers. According to the embodiment, the horizontal span D″ is smaller than or equal to 3000 micrometers, and the routing density of signal traces can be increased.
According to the simulation results of the embodiment for dual coupled impedance (impedance simulation using ANSYS Q2D), a single-ended impedance Z0 of about 48.8Ω-49.1Ω can be achieved. A simulated Zdiff (S1, S2) of about 96.6Ω, a simulated Zdiff (S3, S1) of about 97.4Ω, and a simulated Zdiff (S2, S3) of about 98.2Ω can be achieved. A simulated Zcom (S1, S2) of about 24.7Ω, a simulated Zcom (S3, S1) of about 24.8Ω, and a simulated Zcom (S2, S3) of about 24.6Ω can be achieved.
According to the embodiment, the reference net RN1, the reference net RN2 and the reference net RN3 may be electrically connected to the reference plane RP through the conductive vias V1˜V3, respectively. According to the embodiment of the invention, the conductive via V1 is formed in the insulating build-up layer 210, and the conductive vias V2˜V3 are formed in the insulating build-up layers 210 and 220.
According to the embodiment, the substrate 7 may comprise a core substrate 10. At least four metal layers M1˜M4 in different levels are disposed on one side of the core substrate 10. Although not shown in this figure, it is to be understood that there may be multiple metal layers disposed on the other side of the core substrate 10. The core substrate 10 may comprise copper traces, which are patterned on an insulating core material layer including, but not limited to, FR-4 epoxy dielectric.
As shown in
According to the embodiment of the invention, a trio of signal traces that is composed of a first signal trace S1, a second signal trace S2 and a third signal trace S3 is arranged in the first middle layer M3 and the second middle metal layer M2. The first signal trace S1 is arranged in the second middle metal layer M2, and the second signal trace S2 and the third signal trace S3 are arranged in the first middle layer M3. The first signal trace S1 overlaps with the second reference plane RP-2. According to the embodiment of the invention, the trio of signal traces comprises at least a pair of differential signal traces. According to the embodiment of the invention, the trio of signal traces may be operated greater than 1 Gb/s. According to the embodiment of the invention, the second signal trace S2 and the third signal trace S3 are coplanar.
According to the embodiment of the invention, the reference net RN1 between the second signal trace S2 and the third signal trace S3 as shown in
An insulating build-up layer 220 is laminated on the first middle metal layer M3 and on the insulating build-up layer 210. For example, the insulating build-up layer 220 may comprise prepreg material such as 2113 prepreg, but is not limited thereto. The insulating build-up layer 220 covers the second signal trace S2 and the third signal trace S3. The second middle metal layer M2 is disposed on the insulating build-up layer 220. An insulating build-up layer 230 is laminated on the second middle metal layer M2 and on the insulating build-up layer 220. The second reference plane RP-2 is disposed on the insulating build-up layer 230.
In
According to the embodiment, for example, the line width W1 of the first signal trace S1 may be 76 micrometers. The line widths W2˜W3 of the signal traces S2˜S3 may be 76 micrometers. The line widths GW2˜GW3 of the reference net RN2˜RN3 may be 76 micrometers. According to the embodiment, for example, the spacing GS2-GS3 may be 76 micrometers. The spacing SS between the signal traces S2, S3 may be 400 micrometers. According to the embodiment, for example, the horizontal span D″ may be about 552 micrometers (76 μm+400 μm+76 μm). According to the embodiment, the horizontal span D″ is smaller than or equal to 3000 micrometers, and the routing density of signal traces can be increased.
According to the simulation results of the embodiment for dual coupled impedance (impedance simulation using ANSYS Q2D), a single-ended impedance Z0 of about 49.6Ω-49.9Ω can be achieved. A simulated Zdiff (S1, S2) of about 97.6Ω, a simulated Zdiff (S3, S1) of about 97.0Ω, and a simulated Zdiff (S2, S3) of about 99.1Ω can be achieved. A simulated Zcom (S1, S2) of about 25.5Ω, a simulated Zcom (S3, S1) of about 25.3Ω, and a simulated Zcom (S2, S3) of about 24.8Ω can be achieved.
For example, the substrate 8a may comprise a core substrate 10. At least three metal layers M1˜M3 indifferent levels are disposed on one side of the core substrate 10. For the sake of simplicity, the metal traces embedded in the core substrate 10 are not explicitly shown in
As shown in
According to the embodiment of the invention, a trio of signal traces composed of a first signal trace S1, a second signal trace S2, and a third signal trace S3 is provided. The first signal trace S1 is arranged in the middle metal layer M2 and on the insulating build-up layer 210. The second signal trace S2 and the third signal trace S3 are arranged in the upper metal layer M1. According to the embodiment of the invention, the trio of signal traces comprises at least a pair of differential signal traces. According to the embodiment of the invention, the trio of signal traces may be operated greater than 1 Gb/s. According to the embodiment of the invention, the second signal trace S2 and the third signal trace S3 are coplanar.
According to the embodiment of the invention, a reference net RN1 and a reference net RN2 are arranged in the middle metal layer M2. A reference net RN3 and a reference net RN4 are arranged in the upper metal layer M1. The first signal trace S1 does not overlap with the reference net RN3 or the reference net RN4 when viewed from the above. The second signal trace S2 overlaps with the reference net RN1 and the third signal trace S3 overlaps with the reference net RN2 when viewed from the above. The reference nets RN1˜RN4 may be electrically connected to ground or power. According to the embodiment of the invention, the second signal trace S2, the third signal trace S3 and the reference nets RN3˜RN4 are coplanar. The second signal trace S2 and the third signal trace S3 are separated by the reference nets RN3˜RN4. The reference nets RN3˜RN4 are interposed between the second signal trace S2 and the third signal trace S3. The first signal trace S1, the reference net RN1 and the reference net RN2 are coplanar, and the reference nets RN3˜RN4 don't overlap with the first signal trace S1 in the thickness direction.
An insulating build-up layer 220 is laminated on the middle metal layer M2. For example, the insulating build-up layer 220 may comprise prepreg material such as 2113 prepreg, but is not limited thereto. The upper metal layer M1 is disposed on the insulating build-up layer 220. A solder mask 130 covers the upper metal layer M1 and the exposed upper surface of the insulating build-up layer 220.
In
According to the embodiment, the line width W1 of the first signal trace S1 is smaller than the line widths GW1, GW2 of the reference nets RN1, RN2. According to the embodiment, the line width W1 of the first signal trace S1 is smaller than or equal to the line widths W2, W3 of second signal trace S2, S3.
For example, the line width W1 of the first signal trace S1 may be 76 micrometers, and the line widths W2, W3 of the signal traces S2, S3 may be 100 micrometers. According to the embodiment, for example, the line widths GW1, GW2 of the reference nets RN1, RN2 may be 300 micrometers, and the line widths GW3, GW4 of the reference nets RN3, RN4 may be 100 micrometers. According to the embodiment, for example, the spacing GS1, GS2 between the reference nets RN1˜RN2 and the first signal trace S1 may be 106 micrometers, and the spacing GS3, GS4 between the reference nets RN3, RN4 and the signal traces S2, S3 may be 100 micrometers. According to the embodiment, for example, the spacing GG between the reference nets RN3, RN4 may be 200 micrometers. The spacing GG like a gap in the reference net or plane that is separated into the reference nets RN3, RN4. According to the embodiment, for example, the horizontal span D″ may be about 888 micrometers. According to the embodiment, the horizontal span D″ is smaller than or equal to 3000 micrometers, and the routing density of signal traces can be increased.
According to the simulation results of the embodiment for dual coupled impedance (impedance simulation using ANSYS Q2D), a single-ended impedance Z0 of about 48.5Ω-48.7Ω can be achieved. A simulated Zdiff (S3, S2) of about 96.4Ω, a simulated Zdiff (S2, S1) of about 97.1Ω, and a simulated Zdiff (S1, S3) of about 96.6Ω can be achieved. A simulated Zcom (S3, S2) of about 24.4Ω, a simulated Zcom (S2, S1) of about 24.5Ω, and a simulated Zcom (S1, S3) of about 24.4Ω can be achieved.
According to the embodiment of the invention, the reference nets RN1, RN2 form a first pair of reference nets that sandwich about the first signal trace S1. The reference nets RN1, RN2 may be electrically connected to the reference plane RP through the conductive vias V1, V2, respectively. The reference nets RN3, RN4 form a second pair of reference nets interposed between the second signal trace S2 and the third signal trace S3. The reference nets RN3, RN4 may be electrically connected to the reference nets RN1, RN2 through the conductive vias V3, V4, respectively. According to the embodiment of the invention, the conductive vias V1, V2 are formed in the insulating build-up layer 210 and the conductive vias V3, V4 are formed in the insulating build-up layer 220.
For example, the substrate 8b may comprise a core substrate 10. At least four metal layers M1˜M4 in different levels are disposed on one side of the core substrate 10. For the sake of simplicity, the metal traces embedded in the core substrate 10 are not explicitly shown in
As shown in
According to the embodiment of the invention, a trio of signal traces composed of a first signal trace S1, a second signal trace S2, and a third signal trace S3 is provided. The first signal trace S1 is arranged in the second middle metal layer M2 and on the insulating build-up layer 220. The second signal trace S2 and the third signal trace S3 are arranged in the upper metal layer M1. According to the embodiment of the invention, the trio of signal traces comprises at least a pair of differential signal traces. According to the embodiment of the invention, the trio of signal traces may be operated greater than 1 Gb/s. According to the embodiment of the invention, the second signal trace S2 and the third signal trace S3 are coplanar.
According to the embodiment of the invention, a gap GP is provided in the second reference plane RP-2. The gap GP is located directly under the first signal trace S1. The gap GP may have a gap width that is wider than the line width of the first signal trace S1. For example, the gap GP may have a gap width of about 300 micrometers. According to the embodiment of the invention, the gap GP may separate the second reference plane RP-2 into a first part P1 and a second part P2.
According to the embodiment of the invention, a reference net RN1 and a reference net RN2 are arranged in the second middle metal layer M2. A reference net RN3 is arranged in the upper metal layer M1. The first signal trace S1 is located directly under the reference net RN3. The reference nets RN1˜RN3 may be electrically connected to ground or power. According to the embodiment of the invention, the second signal trace S2, the third signal trace S3 and the reference net RN3 are coplanar. The second signal trace S2 and the third signal trace S3 are separated by the reference net RN3. The reference net RN3 is interposed between the second signal trace S2 and the third signal trace S3. The first signal trace S1, the reference net RN1 and the reference net RN2 are coplanar.
An insulating build-up layer 230 is laminated on the second middle metal layer M2. For example, the insulating build-up layer 230 may comprise prepreg material such as 2113 prepreg, but is not limited thereto. The upper metal layer M1 is disposed on the insulating build-up layer 230. A solder mask 130 covers the upper metal layer M1 and the exposed upper surface of the insulating build-up layer 230.
In
According to the embodiment, the line width W1 of the first signal trace S1 is smaller than the line widths GW1, GW2 of the reference nets RN1, RN2. According to the embodiment, the line width W1 of the first signal trace S1 is smaller than or equal to the line widths W2, W3 of second signal traces S2, S3, and the gap width GP.
For example, the line width W1 of the first signal trace S1 may be 76 micrometers, and the line widths W2, W3 of the signal traces S2, S3 may be 100 micrometers. According to the embodiment, for example, the line widths GW1, GW2 of the reference nets RN1, RN2 may be 200 micrometers, and the line width GW3 of the reference net RN3 may be 100 micrometers. According to the embodiment, for example, the spacing GS1, GS2 between the reference nets RN1, RN2 and the first signal trace S1 may be 162 micrometers, and the spacing GS3, GS4 between the reference net RN3 and the signal traces S2, S3 may be 150 micrometers. According to the embodiment, for example, the horizontal span D″ may be about 800 micrometers. According to the embodiment, the horizontal span D″ is smaller than or equal to 3000 micrometers, and the routing density of signal traces can be increased.
According to the simulation results of the embodiment for dual coupled impedance (impedance simulation using ANSYS Q2D), a single-ended impedance Z0 of about 47.4Ω-50.3Ω can be achieved. A simulated Zdiff (S3, S2) of about 99.0Ω, a simulated Zdiff (S2, S1) of about 91.4Ω, and a simulated Zdiff (S1, S3) of about 96.7Ω can be achieved. A simulated Zcom (S3, S2) of about 25.6Ω, a simulated Zcom (S2, S1) of about 24.6Ω, and a simulated Zcom (S1, S3) of about 26.2Ω can be achieved.
According to the embodiment of the invention, the reference nets RN1, RN2 form a pair of reference nets that sandwich about the first signal trace S1. The reference nets RN1, RN2 may be electrically connected to the first part P1 and the second part P2 of second reference plane RP-2 through the conductive vias V1, V2, respectively. The reference net RN3 is interposed between the second signal trace S2 and the third signal trace S3. According to the embodiment of the invention, the conductive vias V1, V2 are formed in the insulating build-up layer 220. The first part P1 and the second part P2 of the second reference plane RP-2 may be electrically connected to the first reference plane RP-1 through the conductive vias V3, V4, respectively.
For example, the substrate 9 may comprise a core substrate 10. At least five metal layers M1˜M5 in different levels are disposed on one side of the core substrate 10. Although not shown in this figure, it is to be understood that there may be multiple metal layers disposed on the other side of the core substrate 10. The core substrate 10 may comprise copper traces, which are patterned on an insulating core material layer including, but not limited to, FR-4 epoxy dielectric.
As shown in
According to the embodiment of the invention, a trio of signal traces composed of a first signal trace S1, a second signal trace S2, and a third signal trace S3 is provided. The first signal trace S1 is arranged in the middle metal layer M3. The second signal trace S2 is arranged in the middle metal layer M2. The third signal trace S3 is arranged in the upper metal layer M1. According to the embodiment of the invention, the trio of signal traces comprises at least a pair of differential signal traces. According to the embodiment of the invention, the trio of signal traces may be operated greater than 1 Gb/s.
According to the embodiment of the invention, a gap GP is provided in the second reference plane RP-2. The gap GP is located directly under the first signal trace S1. The gap GP may have a gap width that is wider than the line width of the first signal trace S1. For example, the gap GP may have a gap width of about 150 micrometers. According to the embodiment of the invention, the gap GP may separate the second reference plane RP-2 into a first part P1 and a second part P2.
According to the embodiment of the invention, a reference net RN1 is arranged in the middle metal layer M3. A reference net RN2 is arranged in the middle metal layer M2. A reference net RN3 is arranged in the upper metal layer M1. The first signal trace S1 is located directly under the reference net RN2. The reference net RN2 overlaps with the first signal trace S1 and the third signal trace S3 when viewed from the above. The reference nets RN1˜RN3 may be electrically connected to ground or power. According to the embodiment of the invention, the first signal trace S1 and the reference net RN1 are coplanar, the second signal trace S2 and the reference net RN2 are coplanar, and the third signal trace S3 and the reference net RN3 are coplanar.
An insulating build-up layer 230 is laminated on the second middle metal layer M2. For example, the insulating build-up layer 230 may comprise prepreg material such as 2113 prepreg, but is not limited thereto. The upper metal layer M1 is disposed on the insulating build-up layer 230. A solder mask 130 covers the upper metal layer M1 and the exposed upper surface of the insulating build-up layer 230.
In
According to the embodiment, the line width W1 of the first signal trace S1 is smaller than the line widths GW1, GW2 of the reference nets RN1, RN2. According to the embodiment, the line width W1 of the first signal trace S1 is smaller than or equal to the line widths W2, W3 of second signal trace S2, S3. According to the embodiment, the line width GW2 of the reference net RN2 is greater than or equal to the line widths W2, W3 of signal traces S2, S3.
According to the embodiment, for example, the line width W1 of the first signal trace S1 may be 76 micrometers, and the line widths W2, W3 of the signal traces S2, S3 may be 100 micrometers. According to the embodiment, for example, the line width GW1 of the reference net RN1 may be 100 micrometers, the line width GW2 of the reference net RN2 may be 150 micrometers, and the line width GW3 of the reference net RN3 may be 100 micrometers. According to the embodiment, for example, the spacing GS1 between the reference net RN1 and the first signal trace S1 may be 112 micrometers, the spacing GS2 between the reference net RN2 and the second signal trace S2 may be 175 micrometers, and the spacing GS3 between the reference net RN3 and the third signal trace S3 may be 100 micrometers. According to the embodiment, for example, the horizontal span D″ may be about 425 micrometers. According to the embodiment, the horizontal span D″ is smaller than or equal to 3000 micrometers, and the routing density of signal traces can be increased.
According to the simulation results of the embodiment for dual coupled impedance (impedance simulation using ANSYS Q2D), a single-ended impedance Z0 of about 47.9Ω-48.4Ω can be achieved. A simulated Zdiff (S3, S2) of about 94.0Ω, a simulated Zdiff (S3, S1) of about 95.8Ω, and a simulated Zdiff (S2, S1) of about 95.4Ω can be achieved. A simulated Zcom (S3, S2) of about 24.4Ω, a simulated Zcom (S3, S1) of about 24.4Ω, and a simulated Zcom (S2, S1) of about 24.3Ω can be achieved.
According to the embodiment of the invention, the reference net RN1 may be electrically connected to the first part P1 of second reference plane RP-2 through the conductive via V1. The reference net RN3 may be electrically connected to the reference net RN1 through the conductive via V2. According to the embodiment of the invention, the conductive via V1 is formed in the insulating build-up layer 220, and the conductive via V2 is formed in the insulating build-up layers 230 and 240. The first part P1 and the second part P2 of the second reference plane RP-2 may be electrically connected to the first reference plane RP-1 through the conductive vias V3, V4, respectively.
Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.
Claims
1. A substrate having multiple metal layers, comprising:
- a plurality of metal layers disposed in different levels, wherein the plurality of metal layers comprises a lower metal layer, a middle metal layer situated overlying the lower layer, and an upper metal layer situated overlying the middle metal layer;
- a solder mask covering the upper metal layer;
- a reference plane arranged in the lower metal layer;
- a trio of signal traces arranged in the middle metal layer, wherein the trio of signal traces comprises a first signal trace, a second signal trace, a third signal trace, and wherein the trio of signal traces comprises at least a pair of differential signal traces;
- a plurality of reference nets arranged in the middle metal layer, wherein the plurality of reference nets comprises a first reference net, a second reference net, a third reference net, and a fourth reference net; and
- the first signal trace is interposed between the first reference net and the second reference net, the second signal trace is interposed between the second reference net and the third reference net, and the third signal trace is interposed between the third reference net and the fourth reference net.
2. The substrate having multiple metal layers according to claim 1, wherein the trio of signal traces is operated greater than 1 Gb/s.
3. The substrate having multiple metal layers according to claim 1, wherein no metal trace is disposed in the upper metal layer in a region directly above a horizontal span between the first signal trace and the third signal trace.
4. The substrate having multiple metal layers according to claim 1, wherein a horizontal span between the first reference net and the fourth reference net is equal to or smaller than 3000 micrometers.
5. The substrate having multiple metal layers according to claim 1, wherein the reference plane is electrically connected to ground or power, and the plurality of reference nets are electrically connected to the reference plane through a plurality of conductive vias.
6. The substrate having multiple metal layers according to claim 1, wherein the trio of signal traces electrically connects between a connector region and a chip package mounting region on the substrate.
7. The substrate having multiple metal layers according to claim 1, wherein common-mode impedances of the trio of signal traces range between 20Ω and 30Ω.
8. A substrate having multiple metal layers, comprising:
- a plurality of metal layers disposed in different levels, wherein the plurality of metal layers comprises a lower metal layer, a middle metal layer situated overlying the lower layer, and an upper metal layer situated overlying the middle metal layer;
- a solder mask covering the upper metal layer;
- a reference plane arranged in the lower metal layer;
- a trio of signal traces comprising a first signal trace arranged in the upper metal layer and a second signal trace and a third signal trace arranged in the middle metal layer, wherein the trio of signal traces comprises at least a pair of differential signal traces; and
- a first reference net arranged in the middle metal layer between the second signal trace and the third signal trace and directly under the first signal trace.
9. The substrate having multiple metal layers according to claim 8, wherein the trio of signal traces is operated greater than 1 Gb/s.
10. The substrate having multiple metal layers according to claim 8 further comprising a second reference net and a third reference net in the middle metal layer, and wherein the second signal trace is interposed between the first reference net and the second reference net, and the third signal trace is interposed between the first reference net and the third reference net.
11. The substrate having multiple metal layers according to claim 8 further comprising a second reference net and a third reference net in the upper metal layer, and wherein the first signal trace is interposed between the second reference net and the third reference net.
12. The substrate having multiple metal layers according to claim 8, wherein the first signal trace has a line width that is smaller than or equal to that of the first reference net.
13. The substrate having multiple metal layers according to claim 8, wherein the reference plane is electrically connected to ground or power, and the first reference net is electrically connected to the reference plane through a conductive via.
14. The substrate having multiple metal layers according to claim 8, wherein common-mode impedances of the trio of signal traces range between 20Ω and 30Ω.
15. The substrate having multiple metal layers according to claim 8, wherein a horizontal span between the second signal trace and the third signal trace is equal to or smaller than 3000 micrometers.
16. A substrate having multiple metal layers, comprising:
- a plurality of metal layers disposed in different levels, wherein the plurality of metal layers comprises a lower metal layer, a first middle metal layer situated overlying the lower layer, a second middle metal layer situated overlying the first middle metal layer, and an upper metal layer situated overlying the second middle metal layer;
- a first reference plane arranged in the lower metal layer;
- a second reference plane arranged in the upper metal layer;
- a trio of signal traces comprising a first signal trace arranged in the second middle metal layer, and a second signal trace and a third signal trace arranged in the first middle metal layer, wherein the trio of signal traces comprises at least a pair of differential signal traces; and
- a pair of reference nets in the second middle metal layer sandwiching about the first signal trace.
17. The substrate having multiple metal layers according to claim 16, wherein the trio of signal traces is operated greater than 1 Gb/s.
18. The substrate having multiple metal layers according to claim 16, wherein the first and second reference planes are electrically connected to ground or power, and the pair of reference nets are electrically connected to the first or the second reference plane through a plurality of conductive vias.
19. The substrate having multiple metal layers according to claim 16, wherein common-mode impedances of the trio of signal traces range between 20Ω and 3Ω.
20. The substrate having multiple metal layers according to claim 16, wherein a horizontal span between the second signal trace and the third signal trace is equal to or smaller than 3000 micrometers.
21. A substrate having multiple metal layers, comprising:
- a plurality of metal layers disposed in different levels, wherein the plurality of metal layers comprises a lower metal layer, a middle metal layer situated overlying the lower layer, and an upper metal layer situated overlying the middle metal layer;
- a solder mask covering the upper metal layer;
- a reference plane arranged in the lower metal layer;
- a trio of signal traces comprising a first signal trace arranged in the middle metal layer, and a second signal trace and a third signal trace arranged in the upper metal layer, wherein the trio of signal traces comprises at least a pair of differential signal traces; and
- a first pair of reference nets in the middle metal layer sandwiching about the first signal trace.
22. The substrate having multiple metal layers according to claim 21 further comprising:
- a second pair of reference nets in the upper metal layer, wherein the second pair of reference nets is interposed between the second signal trace and the third signal trace, and does not overlap with the first signal trace.
23. The substrate having multiple metal layers according to claim 21 further comprising:
- a reference net in the upper metal layer between the second signal trace and the third signal trace.
24. The substrate having multiple metal layers according to claim 21 further comprising:
- a gap in the reference plane, wherein the gap is located directly under the first signal trace.
25. The substrate having multiple metal layers according to claim 21, wherein the reference plane is electrically connected to ground or power, and the first pair of reference nets are electrically connected to the reference plane through a plurality of conductive vias.
26. The substrate having multiple metal layers according to claim 21, wherein common-mode impedances of the trio of signal traces range between 20Ω and 30Ω.
27. The substrate having multiple metal layers according to claim 21, wherein a horizontal span between the first pair of reference nets is equal to or smaller than 3000 micrometers.
28. A substrate having multiple metal layers, comprising:
- a plurality of metal layers disposed in different levels, wherein the plurality of metal layers comprises a lower metal layer, a first middle metal layer situated overlying the lower layer, a second middle metal layer situated overlying the first middle metal layer, a third middle metal layer situated overlying the second middle metal layer, and an upper metal layer situated overlying the third middle metal layer;
- a first reference plane arranged in the lower metal layer;
- a second reference plane arranged in the first middle metal layer; and
- a trio of signal traces comprising a first signal trace arranged in the second middle metal layer, a second signal trace arranged in the third middle metal layer, and a third signal trace arranged in the upper metal layer, wherein the trio of signal traces comprises at least a pair of differential signal traces.
29. The substrate having multiple metal layers according to claim 28 further comprising:
- a first reference net in the second middle metal layer and in proximity to the first signal trace;
- a second reference net in the third middle metal layer and in proximity to the second signal trace; and
- a third reference net in the upper metal layer and in proximity to the third signal trace, wherein the first signal trace is located directly under the second reference net, and wherein the second reference net overlaps with the first signal trace and the third signal trace.
30. The substrate having multiple metal layers according to claim 28 further comprising:
- a gap provided in the second reference plane, wherein the gap is located directly under the first signal trace.
31. The substrate having multiple metal layers according to claim 30, wherein the gap has a gap width that is wider than a line width of the first signal trace.
32. The substrate having multiple metal layers according to claim 28, wherein the trio of signal traces is operated greater than 1 Gb/s.
33. The substrate having multiple metal layers according to claim 28, wherein the first and second reference planes are electrically connected through a plurality of conductive vias.
34. The substrate having multiple metal layers according to claim 28, wherein common-mode impedances of the trio of signal traces range between 20Ω and 30Ω.
35. The substrate having multiple metal layers according to claim 29, wherein a horizontal span between the second signal trace and the second reference net is equal to or smaller than 3000 micrometers.
Type: Application
Filed: Mar 15, 2018
Publication Date: Jul 19, 2018
Patent Grant number: 10426035
Inventors: Nan-Jang Chen (Hsinchu City), Yau-Wai Wong (Hsinchu County)
Application Number: 15/921,676